1. Field of the Invention
The invention relates to a control unit used for antilock brake systems on automobiles, motorcycles and other vehicles, and particularly to a control unit comprising a support base with hydraulic channels formed therein, an oil tank and electro-magnetic valves which have inlet openings in communication with the hydraulic channels, the valves being supported by the support base and in turn supporting thereon oil tank.
2. Description of the Prior Art
In conventional units as disclosed in Japanese Patent Laid-Open No. 160242/1981, the opening portion in the bottom wall of an oil tank is simply oil-tightly fitted to the upper ends of electro-magnetic valves which are supported on a support base.
With this construction, the supporting strength of the magnetic valves for the oil tank is relatively low, making it difficult to mount an oil tank of a large capacity. Especially when the oil tank is made of a synthetic resin, the oil tank is unable to suppress vibration of the valves which may be caused by repeated opening and closing operations of the valves, and the oil-tightness at the connection of the electro-magnetic valves with the oil tank may be deteriorated due to vibration.
It is also known in the art that there are control units in which, as disclosed in Japanese Patent Publication No. 26220/1974, solenoid valves are clamped from both above and below between a pair of support bases and a pair of clamping plates which are tightly connected together by a plurality of through-bolts, thus constituting a control unit.
In control units of such construction, the clamping plates have to be thick enough so that they will not bend under the tightening force of the through-bolts, since the clamping plates are spaced apart from the support base. The through-bolts also have to be longer than the height of the electro-magnetic valves. As a result the total weight of the unit becomes large; furthermore, there is a disadvantage that the plurality of bolts that stand surrounding the electro-magnetic valves make the outer dimension of the unit large. In addition, in control units of this type, if the hydraulic channel formed in the support base is used for introducing a high pressure oil from the hydraulic pressure source, the hydraulic pressure of that high-pressure hydraulic channel always works on a large area on the end faces of the electro-magnetic valves, developing a thrust load that tends to remove the magnetic valves from the support base. Accordingly, the fixing means as comprising a plurality of through-bolts and clamping plates is subjected to a large load. It is, therefore, necessary that the fixing means be formed with sufficient strength. Also in this case, the weight of the unit is inevitably increased and its size made bulky.